Liquid level gauge



' the foot measurement.

eter coil oiresistance wire or even a wire of sufiicimflyhishremtancemetal. resistoristappedalongiislmgthas ,atintervahequaltothemaiortmitot contact strips l1 omosite the resistor, each slightlylesstbanoneiootlongsoastobeoutoi contact with each other, and in insulated rela-' tion to each other. The fioat is provided with brushes or contactors II and I! adopted to make connection between resistor II and wire l3, and wire I4 and strips II, respectively. The several electrical elements are in insulated relation to the pipe ID.

The electrical indicating system includes a set of relay switches 28, normally open and operable by magnets or solenoids 2|. One switch is provided for each segment oi resistor I, but in the drawing, for the sake of clarity, only four of the switches and their connectiohs are shown. A

modified Wheatstone bridge is provided, includ,-'

ing a multi-point variable resistor 21 for the functioning of the 'device in making a height measurement. The foot determination and the inch deter-' mination are made successively. In Fig.1 the leads that are live, i. e. carry current, for the foot determination are shown in heavy lines. Switches 38 and 29 are at the position shown. This in effect puts the section 01' resistor it between fioat contactor l8 and the bottom in series with resistor 21 to form the unknown arm of a bridge the other three arms oi which are constituted by resistors ll, 32 and 33. The circuit. is as follows: leads 5. and it from the lower end of resistor II and wire I! respectively go to one end of resistor 21, at 52,'and to one end of fixed resistor 23 as shown. Resistors I3, 32 and ll being in series and resistor 2| being connected to arm 29 at 53, the four resistors (16 and 21 being considered as one) are in series connection. Current is applied to this resistance bridge between points 54 and 55, by leads II and 51 in connection with the rectifier as shown. The galvawhenceconnectionismadetooneside Current fiows eontactor II and the co m3 corresponding solenoid Iithroughaleadll.

aleadlltotherectifiencompletingthecircuit through the solenoid and causing the switch 2| toclose. lfthefloatmovestoanotherlevehtbe' is as follows: Points 24 are connected by leads N and II to the corresponding solenoid switch 25, which is in closed position. These solenoid switches are all connected in parallel to lead II (which is live as described in connection with the relay circuit) and lead 8 which is also live. Thus the foot-long section 22 of resistor I. between points 24 nearest the float is energized. Float contactor I8 is connected to one side of the galvanometer through lead 5| as already described and the other side of the galvanometer is connected through switch 39 and a lead I! to the arm 38 of the inch slide-wire 2a, the ends 01 which are connected in parallel with leads I! and' 48 through leads 8'! and 68. Arm 3| is simply turned until the galvanometer comes to zero,

' and then the inches areread 011! the slide wire.

In the example shown the height of the balancing liquid measured is 10' feet 6% inches. 37

-iound. Simple modification oi the bridge circuit 'enablesthe height to be read directl ii desired.

Fig. 3 shows the active circuit during the inch measurement, in simplified manner.

obtain accurate volume measurement it is only necessary to knowthe specific gravity of the tank a liquid at its base temperature. Necessityi'or base nometer is connected across the opposite di-- ing point on resistor 21 (in the example, that marked "10?) gives the foot reading. shows in simplified manner P18; 2 the active circuit in Considering the inch measurement: assuming that the fioat is in the position shown. a relay circuit is completed between the D. C. source .and the corresponding elay switch solenoid 26, as follows: lead 4 from one side of the rectifier.

- temperature correction calculations in stock control is dispensed with. Also, with water there is no deposition of gum or other foreign materials on the resistor and contact elements. It is advantageous to arrange the fioat contactors under the surface of the water, or within a thin layer of pure oil floated on top of the water, to avoid any fire hazard. However, the required currents and voltages are low enough to make the danger of sparking negligible. Ii desired the leg I I can'contain liquid from the tank.

No special calibration oi. the several resistors is required. The contact resistance oi! the relay switches does not enter into the measurements.

V The bridge assembly, galvanometer and energy is connected with wire ll in the manometer. (5

supply can be mountedas a unit at some central point or otherwise where desired If desired such unit can be made portable for application tobalancing legs indistant places. Other-bridge arrangements than that disclosed can be employed tor measuring the 7 5. In liquid level measuring apparatus of the What I claim is:

,1. In a liquid level gage having a leg filled to varying heights with a liquid the height of which is to be measured, an elongated resistor in the leg, float means in the leg responsive to the level of liquid in the leg and provided with an electrical contactor adapted to. makeelectrical contact with the resistor at a point thereon depending upon the level of the liquid and means for measuring the resistance 01' a section of the resistor between one end thereof and said point oi of the water in the tube depends on the height of liquid in the tank, an elongated resistor extending along the interior of the. tube, a float on the column of water provided with a contactor adapted to make electrical contact with the resistor, means for measuring the resistance of the portion of the resistor from one'end of the resistor to the point of contact, a plurality of spaced taps along the resistor and means for measuring the resistance of the section of resistor included between said point of contact and one of the adjacent taps.

3. In liquid level measuring apparatus-of the type described, a leg adapted to contain a relatively non-conductiveliquid filling it to, a variable height, a resistor extending up inside the le and tapped at closely spaced intervals to define plural sections of equal resistance, a float in the leg having a contactor adapted to make contact with the resistor, resistance bridge means for measuring the resistance of the portion of the resistor from one end thereof to the float contactor and resistance bridge means for measuring the section of resistance between the float contactor and one of the adjacent taps.

4. In liquid level measuring apparatus of the class described, a leg adapted to contain a relatively non-conductive liquid filling it to various heights, a resistor extending up the leg and tapped at equal intervals to define sections of equal resistance, a float in the leg having a contactor adapted to make contact with the resistor,

a pair of resistance-measuring means, circuit 1 means for connecting one of the resistancemeasuring means to the float contactor and to one end, of the resistor, for measurement or the resistance of the portion of resistor between said contactor and end, and circuit means for connecting the other resistance-measuring means to the taps on the resistor on each side oi the float contactor, for measurement of the resistance of the portion of the resistor between the float contactor and one of said adjacent taps.

class described, a leg adapted to contain a relatively non-conductive liquid filling it to various heights, a resistor extending up the leg and tapped at equal intervals to define sections of equal resistance, a series of separate contact elements in the leg opposite said sections of the resistor, a float in the leg having a contactor adapted to make contact with the resistor and a contactor adapted to make contact with the contact elements, a resistance measuring means, circuit -means connecting said measuring means with one end of said resistor and with the float resistor contactor, for measurement of the resistance of the portionof the resistor between'said contactor and end, a series of normally open switches each having electrically operable clcs-. ing means, circuit means including a source of electrical energy connecting eachelectrically operable; means with a corresponding leg contact element, whereby on contact oi. the float contact contactor with any one of the leg contacts the corresponding switch is closed, leads connecting each of said equal sections of the resistonto one of said switches, a second resistance measuring means, and circuitmeans connecting each switch to said second resistance measuring means; whereby to measure the resistance of the portion of the section of the resistor between the float contactor and one of the adjacent taps;

6. In liquid level measuring apparatus of the type described, a leg containing a column of'relatively non-conductive liquid, the level of which is to be measured, filling the leg to a variable height, a resistor extending up within the leg and tapped at a plurality of closely spaced inter:

vals to define a plurality of resistance sections, a like plurality of closely spaced'vertically extended conductive elements spaced along the inside of the leg and electrically insulated from each other, a float on the liquid column, provided with one resistor-contactoradapted to make com tact with the resistor, and a separate contactor adapted to make contact with one of the conductive elements, separate electrical leads to the resistor-contactor and to the conductive-element contactor of such character as to maintain electrical connection therewith without interfering with rise and fall of the float,-an electrical re- 'sistance measuring circuit connected to said resistor-contactor lead and to one'end of the re--, sistor, for measuring the resistance of the portion of the resistor from one end thereof to the point of contact-with the resistor-contactor, a

second resistance measuring circuit, and means for connecting the second measuring circuit,

through'said second lead, to that conductive eleinent which is contacted by the float conductive-- element contactor, and to a tap on the resistor adJacent the point of contactor the'resistor contactor, whereby to measure the resistance between said tap and said point.

WILLIAM R. MCCOY. 

